1. Field
The present invention relates generally to communication links and more particularly to a method, system, and computer program product for providing an improved packet structure for Mobile Display Digital Interface (MDDI) links.
2. Background
In the field of interconnect technologies, demand for ever increasing data rates, especially as related to video presentations, continues to grow.
The Mobile Display Digital Interface (MDDI) is a cost-effective, low power consumption, transfer mechanism that enables very-high-speed data transfer over a short-range communication link between a host and a client. MDDI requires a minimum of just four wires plus power for bidirectional data transfer that delivers a maximum bandwidth of up to 3.2 Gbits per second.
In one application, MDDI increases reliability and decreases power consumption in clamshell phones by significantly reducing the number of wires that run across a handset's hinge to interconnect the digital baseband controller with an LCD display and/or a camera. This reduction of wires also allows handset manufacturers to lower development costs by simplifying clamshell or sliding handset designs. Further, differential signaling employed with MDDI reduces electro-magnetic Interference that can occur over traditional parallel connections.
There are some improvements needed to the current MDDI systems. Currently sub-frames contain fixed sub-frame length and timing intervals. This limits the system to a fixed number of bits in each sub-frame and operates at a fixed rate. This prevents packets from spanning from one sub-frame to the next. Large packets must be delayed until the next sub-frame to be transmitted, wasting bandwidth and increasing latency. A system with flexible sub-frame length is needed to more efficiently transmit these large packets. Another improvement over a fixed sub-frame length is the ability to use unlimited sub-frame length when the link comes out of hibernation. This also saves on bandwidth because the sub-frame header packet is transmitted only once to allow the client to sync at startup.
Another improvement needed to the existing systems is a method to avoid repetitive retransmission of certain video packet data when some of the parameters are unchanged. Again, this will save on bandwidth. This is accomplished by providing a windowless video stream packet. Additionally, a system is needed to provide a way to specify what fields are contained within a video stream packet when some values have not changed. It would waste bandwidth to repeatedly retransmit the fields that contain values identical to those sent in previous packets. This is provided in a packet contents field of the flexible video stream packet.
Existing systems first transmit a round trip delay measurement packet and then transmit a separate reverse encapsulation packet in order for the host to receive data from the client. The presently claimed invention is a significant improvement over the present systems and combines the functionality of the two packets into a single enhanced reverse encapsulation packet.